"Personally, I'd say that a better idea would be to keep the present system, but make withholding illegal."
Ok, let's take a look at that option. We currently have a tax system that
(1) imposes hundreds of billions of dollars in compliance costs on taxpayers as a whole, and
(2) puts US producers at a disadvantage vs their international counterparts, not only in foreign markets, but even here in our own country.
There are many more problems with the current system, but let's limit it to those two for now. Your proposal (which has no chance politically, but that's another discussion) would do nothing about either of the problems outlined above.
So is it your position that we should continue with a system that is growing like a cancer in size and complexity and imposes constantly higher and higher compliance costs on all of us? And is it your position that, as a matter of public policy, we should make it as difficult as possible for US producers to compete with their international counterparts and that we should watch as our trade deficit expands each year? Should we do nothing to stop the loss of good jobs from this country?